Massive pulmonary embolism post decannulation from Extra Corporeal Membrane Oxygenation: an unexpected complication

ABSTRACT

Introduction: Massive pulmonary embolism is a rare complication following Veno-Venous Extra Corporeal Membrane Oxygenation (VV-ECMO) decannulation. Management can be challenging. The authors present a case that required VV-ECMO re-cannulation and catheterdirected thrombolysis. Main body 58-year-old gentleman, background of hypertension and asthma, admitted with severe respiratory failure secondary to COVID-19 pneumonitis. Due to lack of improvement with conventional ARDS treatment, he was referred and retrieved on VV-ECMO. After being off sweep gas for more than 24 hours he was decannulated on day 7. Five hours after decannulation the patient acutely deteriorated. He became tachycardic, hypotensive and hypoxic. A bedside TTE showed severely dilated and impaired right ventricle. The patient was started on milrinone and nitric oxide. Nevertheless, he deteriorated further and became profoundly hypoxic and hypercapnic, and a decision was made to start him on VV-ECMO. A TOE was done to guide cannulation and showed a thrombus in the RV and in the left pulmonary artery. Next day, a CT-pulmonary angiogram (CTPA) was done which showed saddle-shaped pulmonary embolism, with a large occlusive clot in the left main pulmonary artery causing complete non-perfusion of the left lung. After a multi-disciplinary team discussion, the patient had catheterdirected thrombolysis, with some haemodynamic improvement. Within 48 hours, TTE was repeated showing no significant improvement on RV function. CTPA showed very mild decrease of the clot burden. Decision was made to repeat catheter-directed thrombolysis and partial thrombectomy. Repeated imaging revealed decrease in the size of the left main pulmonary artery thrombus. It is thought that the massive pulmonary embolism could have been caused by showering of ECMO cannulas-related thrombi, which were dislodged during decannulation. Patient remained on VV-ECMO for 32 days and was decannulated successfully afterwards and was discharged home on apixaban and long-term pulmonary hypertension follow-up. Conclusion: ECMO cannulas related thrombi are not uncommon complications because of prolonged stay and coagulopathy related to ECMO circuit. However, massive embolism is rarely seen. The use of echocardiography was paramount on the differential diagnosis. In this TTE study, the right ventricle looks significantly dilated with severely impaired both longitudinal and radial functions. Additionally noted septal flattening in systole indicating RV pressure overload, diastolic notching of RVOT doppler trace consistent with significantly raised pulmonary artery pressure and mild to moderate tricuspid regurgitation. Otherwise, the left ventricle is small and has preserved function. (Figure Presented).